Cermatulus nasalis is native flat brown soldier bug that is 7.2-11.5 mm long. It also found in Australia.C. nasalis looks like a small version of Nezara viridula (the green vegetable bug) except that it is dark brown with a yellow crescent mark on its back, between the wings. It is a predatory insect that feeds by spearing its prey with a long hollow beak and liquefy the prey's insides with saliva and then it sucks out the contents.The females lay small round black eggs that have short white spines around their rim. They are laid in a batch on leaves or tree trunks.Like most other true bugs C. nasalis has five instars stages.When the eggs hatch the 1st instars have a black head and a bright red body. They initially feed on bacteria which the female had deposited on the eggs when she laid them. These first instars nymphs also feed on plant juices.The 2nd instars start feeding on soft body insects such as caterpillars.The 3rd, 4th and 5th instars are like their adults essentially predaceous. They also feed on other soft body insects. They have an orange band behind their head and distinctive black patches along the centre and around the lower sides of a red abdomen.

Cermatulus nasalis is not liked by Monarch butterfly enthusiasts because they feed predominantly on caterpillars but these shield bugs are an important predator, as they destroy many pest species such as the Paropsis charybdis (Eucalyptus Tortoise Beetle).